LONDON – Three former international prosecutors have accused Syria of large-scale killing and torture in a report — based on evidence of a defector — commissioned by Qatar, which backs Syrian rebels, The Guardian and CNN reported Monday.

The report, which can be found online at both news outlets, relies on the unauthenticated testimony and photos given by the source, who remains unidentified for security purposes.

The release came a day before talks were due to be held in Geneva aimed at negotiating an end to Syria’s bloody civil war.

The informant, a photographer who claims to have defected from the Syrian military police, presented forensic experts commissioned by the London legal firm representing Qatar with around 55,000 digital images of 11,000 dead detainees. He claims they died in captivity before being taken to a military hospital to be photographed.

“Overall there was evidence that a significant number of the deceased were emaciated and a significant minority had been bound and/or beaten with rod-like objects,” said the report.

Some had no eyes while others showed signs of strangulation or electrocution, according to the 31-page document.

The report was written by Desmond de Silva, former chief prosecutor of the special court for Sierra Leone; Geoffrey Nice, the former lead prosecutor in the trial of former Yugoslavian President Slobodan Milosevic; and David Crane, who indicted Liberian President Charles Taylor.

De Silva told The Guardian that the evidence provides the “smoking gun” proving that the regime of President Bashar Assad had carried out “industrial-scale killing.”

Crane called the evidence “amazing” and suggested there was a strong case for prosecution.

“Now we have direct evidence of what was happening to people who had disappeared,” he explained. “This is the first provable, direct evidence of what has happened to at least 11,000 human beings who have been tortured and executed and apparently disposed of.”

Sunni Qatar was quick to back rebels who rose up in 2011 against the rule of Assad, who is backed by Shiite powerhouse Iran.